Spectrally combined four-diode-pumped femtosecond Ti:sapphire laser with 16.3 nJ pulse and its application to video-rate coherent anti-Stokes Raman scattering spectro-microscopy.

We demonstrate the generation of high-energy femtosecond pulses by a spectrally combined four-diode-pumped Ti:sapphire laser with semi-conductor saturable absorber mirror mode locking. To achieve energy scaling, the laser cavity was extended using a design based on the Herriott multipass cell. The laser operates at a 17.5 MHz repetition rate and generates pulses with energies as high as 16.3 nJ and 80 fs in duration. The signal-to-noise ratio at the fundamental frequency showed an extinction ratio of >50 dB relative to the carrier. This compact single laser was applied to video-rate forward and backward coherent anti-Stokes Raman scattering spectro-microscopy with a pixel dwell time of 122 ns, which is the lowest dwell time ever achieved, to the best of our knowledge.

Spectrally combined three-diode-pumped compact femtosecond Ti:sapphire laser exceeding 1 W mode-locked power.

The achievement of a high average power exceeding 1 W remains a major challenge for direct-diode pumped and mode-locked femtosecond Ti:sapphire lasers. Herein, we demonstrate high-power soliton-like pulses from a direct spectrally combined three-diode-pumped and semiconductor saturable absorber mirror (SESAM)-based mode-locked Ti:sapphire laser. Its mode-locked output power of up to 1 W was obtained in correspondence with a 68.8 MHz repetition rate and 55 fs pulse duration; thus, the pulse energy and peak power are 14.5 nJ and 264 kW, respectively. To the best of our knowledge, this is the highest reported output power and pulse energy from a Ti:sapphire laser with three spectrally combined pump diodes (471 nm, 491 nm, and 525 nm) and a simple beam expander. For efficient pumping, the combined pump beam, directed into the lens (f = 60 mm), which comprised three aspheric lenses along the fast axis and a shared cylindrical beam telescope (8× magnification) along the slow axis, resulting in a circular-focused beam in the Ti:sapphire crystal. The beam waist was measured to be 39 µm ×38 µm along the slow and fast axes.

Baumann Skin Type in the Korean Male Population.

BACKGROUND: Research into the Baumann skin type (BST) has recently expanded, with growing interest in the development of an efficient and effective skin type classification system for better understanding of this skin condition. OBJECTIVE: We aimed to identify male-specific skin type characteristics with investigation into the distribution of BST by age and region in the Korean male population and to determine the intrinsic and extrinsic factors related to skin type. METHODS: A questionnaire was administered to collect information about age, region, working behavior, drinking behavior, smoking behavior, usual habit of sun protection, medical history, and the BST which consisted of four parameters; oily (O) or dry (D), sensitive (S) or resistant (R), pigmented (P) or non-pigmented (N), and wrinkled (W) or tight (T). RESULTS: We surveyed 1,000 Korean males aged between 20 and 60 years who were divided equally by age and region. Of the total respondents, OSNW type accounted for the largest percentage and ORPW type the lowest. In terms of Baumann parameters, O type was 53.5%, S type was 56.1%, N type was 84.4% and W type was 57.5%. Several behavioral factors were found to have various relationships with the skin type. CONCLUSION: The predominant skin type in the Korean male respondents was OSNW type, and the distribution of skin types with regards to age and region was reported to be distinct. Therefore, skin care should be customized based on detailed skin types considering the various environmental factors.

Baumann Skin Type in the Korean Female Population.

BACKGROUND: To meet the need for a subspecialized skin type system, the Baumann skin type (BST) system was proposed. OBJECTIVE: To evaluate the distribution of BST types and influencing factors among Korean women. METHODS: BST questionnaires were administered to 1,000 Korean women. The possible responses were as follows: oily (O) or dry (D), sensitive (S) or resistant (R), pigmented (P) or non-pigmented (N), and wrinkled (W) or tight (T). The correlations of the BST with the subjects' age, location, ultraviolet (UV) ray exposure, drinking and smoking habits, and blood type were assessed. RESULTS: The OSNT, DSNT, DRNT, and OSNW skin types were the most common skin types (55.3%). The O, S, P, and W types accounted for 46.6%, 68.8%, 23.2%, and 31.9%, respectively. The proportion of the O and S type was the highest in Gyeongsangbuk-do (55.0%) and Seoul (77.2%). The proportion of the P and W type was the highest in Gyeongsangbuk-do (33.0%) and Chungcheong-do (39.0%). The O type decreased in the higher age group, whereas the P and W type showed a reversed tendency. In smokers, the proportion of W type was significantly higher than in the non-smokers (66.3% vs. 24.1%, p<0.05). CONCLUSION: The 4 most common BST types were OSNT, DSNT, DRNT, and OSNW. In the comparison across the 4 BST parameters according to the age, region, smoking and drinking habits, occupation, blood type, and UV exposure, significant differences were observed. Individualized and customized skin care is required according to the personal skin type.

Photoacoustic imaging probe for detecting lymph nodes and spreading of cancer at various depths.

We propose a compact and easy to use photoacoustic imaging (PAI) probe structure using a single strand of optical fiber and a beam combiner doubly reflecting acoustic waves for convenient detection of lymph nodes and cancers. Conventional PAI probes have difficulty detecting lymph nodes just beneath the skin or simultaneously investigating lymph nodes located in shallow as well as deep regions from skin without any supplementary material because the light and acoustic beams are intersecting obliquely in the probe. To overcome the limitations and improve their convenience, we propose a probe structure in which the illuminated light beam axis coincides with the axis of the ultrasound. The developed PAI probe was able to simultaneously achieve a wide range of images positioned from shallow to deep regions without the use of any supplementary material. Moreover, the proposed probe had low transmission losses for the light and acoustic beams. Therefore, the proposed PAI probe will be useful to easily detect lymph nodes and cancers in real clinical fields.

Correction: Mitochondrial Morphology and Fundamental Parameters of the Mitochondrial Respiratory Chain Are Altered in Caenorhabditis elegans Strains Deficient in Mitochondrial Dynamics and Homeostasis Processes.

[This corrects the article DOI: 10.1371/journal.pone.0130940.].

Gain-switched Ti:sapphire laser-based photoacoustic imaging.

We demonstrate photoacoustic (PA) imaging using a compact gain-switched Ti:sapphire laser. Additionally, a simple laser configuration is provided. The Ti:sapphire laser is pumped using a frequency-doubled pulsed neodymium-doped yttrium aluminum garnet pulse laser operating at a repetition rate of 10 Hz, with a pump energy of 37 mJ. No water cooling is required for the Ti:sapphire crystal. The output pulse energy and pulse duration of the laser are 13.6 mJ and 11 ns, respectively. Thus, the power conversion efficiency is 36.7%. As the end mirror in a laser cavity is adjusted in a horizontal direction, the output wavelength can be tuned within a range of 725-880 nm with a spectral bandwidth of approximately 1 nm. The laser has a small footprint size of 50 cm×35 cm including even laser pumping. Because the near-infrared region has significant advantages in the context of absorption and scattering in biological tissues, our laser can be used for PA imaging. Apart from obtaining PA images of a tube filled with indocyanine green immersed in water and placed under chicken breast tissue, our laser system could also be used for the simultaneous PA and ultrasound (US) dual-modality imaging of blood vessels lying beneath the skin of a human middle finger. We used a commercially available US machine for the PA and US dual-modality imaging.

1,3-Dinitrobenzene neurotoxicity - Passage effect in immortalized astrocytes.

Age-related disturbances in astrocytic mitochondrial function are linked to loss of neuroprotection and decrements in neurological function. The immortalized rat neocortical astrocyte-derived cell line, DI-TNC1, provides a convenient model for the examination of cellular aging processes that are difficult to study in primary cell isolates from aged brain. Successive passages in culture may serve as a surrogate of aging in which time-dependent adaptation to culture conditions may result in altered responses to xenobiotic challenge. To investigate the hypothesis that astrocytic mitochondrial homeostatic function is decreased with time in culture, low passage DI-TNC1 astrocytes (LP; #2-8) and high passage DI-TNC1 astrocytes (HP; #17-28) were exposed to the mitochondrial neurotoxicant 1,3-dinitrobenzene (DNB). Cells were exposed in either monoculture or in co-culture with primary cortical neurons. Astrocyte mitochondrial membrane potential, morphology, ATP production and proliferation were monitored in monoculture, and the ability of DI-TNC1 cells to buffer K(+)-induced neuronal depolarization was examined in co-cultures. In HP DI-TNC1 cells, DNB exposure decreased proliferation, reduced mitochondrial membrane potential and significantly decreased mitochondrial form factor. Low passage DI-TNC1 cells effectively attenuated K(+)-induced neuronal depolarization in the presence of DNB whereas HP counterparts were unable to buffer K(+) in DNB challenge. Following DNB challenge, LP DI-TNC1 cells exhibited greater viability in co-culture than HP. The data provide compelling evidence that there is an abrupt phenotypic change in DI-TNC1 cells between passage #9-16 that significantly diminishes the ability of DI-TNC1 cells to compensate for neurotoxic challenge and provide neuroprotective spatial buffering. Whether or not these functional changes have an in vivo analog in aging brain remains to be determined.

Mitochondrial Morphology and Fundamental Parameters of the Mitochondrial Respiratory Chain Are Altered in Caenorhabditis elegans Strains Deficient in Mitochondrial Dynamics and Homeostasis Processes.

Mitochondrial dysfunction has been linked to myriad human diseases and toxicant exposures, highlighting the need for assays capable of rapidly assessing mitochondrial health in vivo. Here, using the Seahorse XFe24 Analyzer and the pharmacological inhibitors dicyclohexylcarbodiimide and oligomycin (ATP-synthase inhibitors), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (mitochondrial uncoupler) and sodium azide (cytochrome c oxidase inhibitor), we measured the fundamental parameters of mitochondrial respiratory chain function: basal oxygen consumption, ATP-linked respiration, maximal respiratory capacity, spare respiratory capacity and proton leak in the model organism Caenhorhabditis elegans. Since mutations in mitochondrial homeostasis genes cause mitochondrial dysfunction and have been linked to human disease, we measured mitochondrial respiratory function in mitochondrial fission (drp-1)-, fusion (fzo-1)-, mitophagy (pdr-1, pink-1)-, and electron transport chain complex III (isp-1)-deficient C. elegans. All showed altered function, but the nature of the alterations varied between the tested strains. We report increased basal oxygen consumption in drp-1; reduced maximal respiration in drp-1, fzo-1, and isp-1; reduced spare respiratory capacity in drp-1 and fzo-1; reduced proton leak in fzo-1 and isp-1; and increased proton leak in pink-1 nematodes. As mitochondrial morphology can play a role in mitochondrial energetics, we also quantified the mitochondrial aspect ratio for each mutant strain using a novel method, and for the first time report increased aspect ratios in pdr-1- and pink-1-deficient nematodes.

Effects of local pH on the formation and regulation of cristae morphologies.

Cristae, folded subcompartments of the inner mitochondrial membrane (IMM), have complex and dynamic morphologies. Since cristae are the major site of adenosine triphosphate synthesis, morphological changes of cristae have been studied in relation to functional states of mitochondria. In this sense, investigating the functional and structural significance of cristae may be critical for understanding progressive mitochondrial dysfunction. However, the detailed mechanisms of the formation and regulation of these cristae structures have not been fully elucidated. Among the hypotheses concerning the regulation of cristae morphologies, we exclusively investigate the effects of the local pH gradient on the cristae morphologies by using a numerical model. An area-difference induced curvature of the membrane is modeled as a function of local pH. This curvature is then applied to the finite element model of a closed lipid bilayer in order to find the energetically favorable membrane configuration. From this study, we substantiate the hypothesis that a tubular crista structure can be formed and regulated by the local pH gradient. Through the simulations with various initial conditions, we further demonstrate that the diameter of a crista is mainly determined by the local pH gradient, and the energetically favorable direction of crista growth is perpendicular to the longitudinal axis of a mitochondrion. Finally, the simulation results at the mitochondrial scale suggest that the cristae membrane may have a lower local pH value and/or a higher cardiolipin composition than the other parts of the IMM.

Biophysical significance of the inner mitochondrial membrane structure on the electrochemical potential of mitochondria.

The available literature supports the hypothesis that the morphology of the inner mitochondrial membrane is regulated by different energy states, that the three-dimensional morphology of cristae is dynamic, and that both are related to biochemical function. Examination of the correlation between the inner mitochondrial membrane (IMM) structure and mitochondrial energetic function is critical to an understanding of the links between mesoscale morphology and function in progressive mitochondrial dysfunction such as aging, neurodegeneration, and disease. To investigate this relationship, we develop a model to examine the effects of three-dimensional IMM morphology on the electrochemical potential of mitochondria. The two-dimensional axisymmetric finite element method is used to simulate mitochondrial electric potential and proton concentration distribution. This simulation model demonstrates that the proton motive force (Δp) produced on the membranes of cristae can be higher than that on the inner boundary membrane. The model also shows that high proton concentration in cristae can be induced by the morphology-dependent electric potential gradient along the outer side of the IMM. Furthermore, simulation results show that a high Δp is induced by the large surface-to-volume ratio of an individual crista, whereas a high capacity for ATP synthesis can primarily be achieved by increasing the surface area of an individual crista. The mathematical model presented here provides compelling support for the idea that morphology at the mesoscale is a significant driver of mitochondrial function.